Turbine exhaust case mixer of gas turbine with variable thickness
A mixer of a bypass turbine aeroengine according to one embodiment, includes circumferential inner and outer flow surfaces in a wavy configuration to form a plurality of lobes of the mixer. The mixer has an upstream end portion of sheet metal with a first thickness and a downstream end portion of sheet metal with a second thickness less than the first thickness.
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The application relates generally to gas turbine aeroengines and, more particularly, to an improved turbine exhaust case mixer for such engines.
BACKGROUND OF THE ARTIn order to increase the effective thrust of turbojet engines, bladed fans have been added to a turbine driven shaft thereof to effect the flow of a quantity of atmospheric air through an annular bypass duct surrounding the turbojet. Hot gases from the core engine and the bypass air stream are mixed together before expulsion through a single nozzle. In order to perform the mixing function, turbine exhaust case (TEC) mixers have been devised which include circumferential inner and outer flow surfaces extending between upstream and downstream ends of the mixer. The inner and outer flow surfaces have a twist extending toward the downstream end to form a plurality of lobes of the mixer, each of the lobes defining an internal passageway along the inner flow surface for the exhaust gases flowing through the mixer and each pair of adjacent lobes defining therebetween an external passageway along the outer flow surface for the bypass air stream. In order to maintain the strength of the mixer while minimizing its weight, it has become common practice to form the mixer from a single sheet of structural material. However, stiffener rings may be required on the mixer in order to restrain its end motion when the mixer is directly welded on the outer duct of a TEC, particularly in large sized turbine machinery engines, in an effort to avoid durability issues due to mixer vibratory responses.
Accordingly, there is a need to provide an improved TEC mixer.
SUMMARYIn one aspect, there is provided a mixer of a bypass turbine aeroengine for mixing exhaust gases discharged from a turbine exhaust case, with a bypass air stream, the mixer defining a central axis extending between an upstream end and a downstream end and comprising circumferential inner and outer flow surfaces extending between the upstream and downstream ends of the mixer, the inner and outer flow surfaces having a wavy configuration extending toward the downstream end to form a plurality of lobes of the mixer, each of the lobes defining an internal passageway along the inner flow surface for the exhaust gases flowing through the mixer and each pair of adjacent lobes defining therebetween an external passageway along the outer flow surface for the bypass air stream flowing through the mixer, the mixer having a circumferentially-endless upstream portion of sheet metal with a first thickness, a circumferentially-endless downstream portion of sheet metal with a second thickness less than the first thickness, and a weld joint extending circumferentially between and joining the circumferentially-endless upstream and downstream portions together.
In another aspect, there is provided method for making a mixer of a bypass turbine aeroengine, the mixer defining a central axis extending between an upstream end and a downstream end and having circumferential inner and outer flow surfaces extending between the upstream and downstream ends of the mixer, the inner and outer flow surfaces having a wavy configuration extending toward the downstream end to form a plurality of lobes of the mixer, each of the lobes defining an internal passageway along the inner flow surface for exhaust gases flowing through the mixer and each pair of adjacent lobes defining therebetween an external passageway along the outer flow surface for a bypass air stream, the method comprising: a) preparing a first group of sheet metal blanks having a first thickness and a second group of sheet metal blanks having a second thickness less than the first thickness of the first group of sheet metal blanks; b) welding each one of the first group of sheet metal blanks to one of the second group of sheet metal blanks to thereby form a plurality of integrated blank-pieces each having a first portion thicker than a second portion; c) shaping the respective integrated blank-pieces into substantially identical circumferential segments of the mixer, each circumferential segment of the mixer including a section of the upstream end of the mixer formed with the first portion of one integrated blank-piece and a section of the downstream end of the mixer formed with the second portion of said one integrated blank-piece; and d) welding together the plurality of circumferential segments in a circumferential array to form the mixer in a complete configuration of a nozzle.
Further details of these and other aspects of the described subject matter will be apparent from the detailed description and drawings included below.
Reference is now made to the accompanying figures in which:
It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
DETAILED DESCRIPTIONReferring to
In one embodiment, the mixer 30 may include a circumferentially-endless upstream portion 50 of sheet metal and a circumferentially-endless downstream portion 52 of sheet metal, as shown in
Referring to
The circumferentially extending weld joints 53 may substantially determine a radial cross-sectional plane substantially normal to the central axis 34 of the mixer 30, as indicated by line 59 in
In one embodiment, each of the circumferential segments 54 may include one complete external passageway 48 as illustrated in
In the above-embodiments shown in
It should be noted that in contrast to a progressively wavy or twisted configuration of the downstream end 38 of the mixer 30, the upstream end 36 of the mixer 30 has a substantially smoothly round or un-twisted configuration in order to provide an interface fitting with the downstream end (not numbered) of an outer duct of the TEC 28.
A method of fabricating such a mixer 30 with variable thicknesses is further described below.
Referring to
A blending process may be conducted to blend the weld joint 53 in order to provide a smooth transition between the surfaces of the respective sheet metal blank 58 and sheet metal blank 60 on both sides of the integrated blank-piece 62. In a shaping process, the respective integrated blank-pieces 62 may be shaped for example by a pressing machine, into substantially identical circumferential segments 54, as shown in
As already described, the shaped circumferential segment 54 may include at least one of a complete internal passageway 46 and a complete external passageway 48 but it should be understood that a single integrated blank-piece 62 may have a circumferential dimension large enough to shape a relatively large circumferential segment in order to include more than one external passageway 48 or more than one internal passageway 46. In such a case, the sheet metal blanks 58 in the first group and the sheet metal blanks 60 in the second group and thus formed integrated blank-piece 62, may be prepared with relatively wide dimensions.
In a welding process the circumferential segments 54 are welded together in a circumferential array to form the mixer 30 in a complete configuration of a nozzle. In such a welding process, each of the weld joints 56 are applied along the interface of two facing side edges of a pair of adjacent circumferential segments 54. It may be convenient for access in the welding process, if the interface of two facing side edges of the adjacent circumferential segments 54 is positioned on the internal passageway 46 (as shown in
Prior to welding the complete mixer 30 to the TEC 28, the upstream end 36 of the complete mixer 30 may be cut and blended for a uniform face ready to be welded to an outer duct of the TEC 28 of the aeroengine. The mixer 30 fabricated according to the above-described embodiments has a relatively simple design architecture and saves manufacturing costs. The mixer 30 having variable thicknesses, provides enhanced rigidity while remaining relatively light weight and therefore may be attached to the TEC of the aeroengine by a single weld joint along the upstream end of the mixer 30 without additional support, resulting in reduced part count on the TEC assembly.
The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the described subject matter. Modifications which fall within the scope of the described subject matter will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.
Claims
1. A mixer of a bypass turbine aeroengine for mixing exhaust gases discharged from a turbine exhaust case with a bypass air stream, the mixer defining a central axis and extending between an upstream end of the mixer and a downstream end of the mixer and comprising: a circumferentially endless upstream portion of a sheet metal including the upstream end, the sheet metal of the circumferentially endless upstream portion having a first thickness being constant along an entire length of the circumferentially endless upstream portion, a circumferentially endless downstream portion of a sheet metal including the downstream end, the sheet metal of the circumferentially endless downstream portion having a second thickness being constant along an entire length of the circumferentially endless downstream portion and being less than the first thickness, circumferential inner and outer flow surfaces extending between the upstream and downstream ends of the mixer, the circumferential inner and outer flow surfaces having a wavy configuration to form a plurality of lobes extending downstream from a location in the circumferentially endless upstream portion and terminating at the downstream end, each of the plurality of lobes defining an internal passageway along the circumferential inner flow surface for the exhaust gases flowing through the mixer and each adjacent pair of the plurality of lobes defining therebetween an external passageway along the circumferential outer flow surface for the bypass air stream flowing through the mixer, and a weld joint located within the wavy configuration and extending circumferentially between the circumferentially endless upstream and downstream portions and joining an upstream section and a downstream section of each of said plurality of lobes.
2. The mixer as defined in claim 1 comprising a plurality of identical circumferential segments and a plurality of axial weld joints each extending from the upstream end to the downstream end and joining an adjacent two of the plurality of identical circumferential segments together, each of the plurality of identical circumferential segments including a circumferential section of the circumferentially endless upstream portion and a circumferential section of the circumferentially endless downstream portion joined by a circumferential section of the weld joint.
3. The mixer as defined in claim 2 wherein each of the axial weld joints in combination with the central axis, determines an axial cross-sectional plane of the mixer.
4. The mixer as defined in claim 2 wherein each of the plurality of identical circumferential segments comprises at least one of the internal passageways or at least one of the external passageways.
5. The mixer as defined in claim 2 wherein each of the plurality of identical circumferential segments comprises at least one external passageway.
6. The mixer as defined in claim 1 wherein the circumferentially extending weld joint determines a radial cross-sectional plane normal to the central axis of the mixer.
7. The mixer as defined in claim 1 wherein the upstream end is a smoothly round configuration.
3053340 | September 1962 | Kutney |
3730292 | May 1973 | MacDonald |
3861140 | January 1975 | Krabacher |
4302934 | December 1, 1981 | Wynosky et al. |
4335801 | June 22, 1982 | Stachowiak et al. |
4576002 | March 18, 1986 | Mavrocostas |
4786016 | November 22, 1988 | Presz, Jr. et al. |
4813230 | March 21, 1989 | Braithwaite |
4819425 | April 11, 1989 | Farquhar et al. |
4909346 | March 20, 1990 | Torkelson |
5265807 | November 30, 1993 | Steckbeck et al. |
5761900 | June 9, 1998 | Presz, Jr. |
5884472 | March 23, 1999 | Presz, Jr. et al. |
6233920 | May 22, 2001 | Presz, Jr. |
6786037 | September 7, 2004 | Balzer |
6935098 | August 30, 2005 | Bardagi et al. |
7017331 | March 28, 2006 | Anderson |
7043898 | May 16, 2006 | Rago |
7100358 | September 5, 2006 | Gekht et al. |
7251927 | August 7, 2007 | Anderson |
7434384 | October 14, 2008 | Lord et al. |
7882696 | February 8, 2011 | Anderson et al. |
8408011 | April 2, 2013 | Fontaine et al. |
8443515 | May 21, 2013 | Morenko et al. |
8739513 | June 3, 2014 | Lefebvre et al. |
20040068981 | April 15, 2004 | Siefker et al. |
20100005780 | January 14, 2010 | Philippe et al. |
20110036068 | February 17, 2011 | Lefebvre et al. |
20110126512 | June 2, 2011 | Anderson |
- Mengle et al., “Lobed Mixer Design for Noise Suppression Acoustic and Aerodynamic Test Data Analysis (2002)”, NASA, NASA/CR--2002-210823/vol. 1.
- Head et al., Hot-Flow Tests of a Series of 10-Percent Scale Turbofan Forced Mixing Nozzles [Jan. 1984], NASA, Technical Paper 2268.
Type: Grant
Filed: Sep 17, 2012
Date of Patent: Jan 29, 2019
Patent Publication Number: 20140075919
Assignee: Pratt & Whitney Canada Corp. (Longueuil, Quebec)
Inventors: Eric Durocher (Vercheres), Guy Lefebvre (St-Bruno de Montarville)
Primary Examiner: William H Rodriguez
Assistant Examiner: Jason H Duger
Application Number: 13/621,467
International Classification: F02K 1/48 (20060101); B21D 53/92 (20060101);